Counter flow genka head

Claim 2

An extruder cross-head assembly for extruding a jacket or cover around a traveling core including in combination a guide through which the core passes, a supply passage through which covering material is supplied to the cross-head assembly at high temperature and pressure, branch passage leading from the supply passage circumferentially to locations on opposite sides of the core guide, a longitudinally extending passage having separate parts communicating with the branch passages at said locations, said longitudinally extending passage extending first rearwardly counter to the direction of movement of the core and then forwardly in the direction of movement of the core, the separate parts of said longitudinally extending passage diverging to greater circumferential angular width as they extend away from said branch passages and eventually combining with one another to surround the full circumferential angular extent of the core guide, and a die into the longitudinally extending passage discharges covering material at substantially uniform velocity around the circumferential extent of the traveling core.

Claim 3

The extruder cross-head assembly described in claim 1 characterized by each of said separate parts of the longitudinally extending passage diverging to a circumferential extent of 180* so that they meet and embrace a 360* extent of discharge for the covering material within the distance that said separate parts of the passage extend in directions counter to the direction of movement of the core.

Claim 4

The extruder cross-head assembly described in claim 1 characterized by the branch passages extending in directions that have a component which is parallel to the direction of movement to the core through the cross-head assembly.

Claim 5

The extruder cross-head assembly described in claim 1 characterized by the cross-head assembly including a cross-head, a helicoid within the cross-head and surrounding the core guide, the branch passages having grooves in the helicoid that are closed along most of their length by overlying surfaces of the cross-head, the supply passage opening through the cross-head into communication with the branch passages where they come together.

Claim 6

The extruder cross-head assembly described in claim 1 characterized by the sum of the cross sections of the branch passages, the combined cross sections of the separate parts of the longitudinally extending passages, and the rest of the longitudinally extending passage to the region of an extrusion die being the same cross-section so that the velocity of the coating material and the pressure drop therein is substantially uniform throughout the flow path of the coating material through the cross-head assembly.

Claim 7

The cross-head assembly described in claim 5 characterized by the radial depth and circumferential width of the various portions of the passages varying oppositely to maintain the cross-sections of the flow path substantially equal along the full length thereof from the supply passage to the entrance into the extruder die.

Claim 8

The extruder cross-head assembly described in claim 1 characterized by the cross-head assembly including a helicoid with surfaces that form part of the wall of the branch passages and the longitudinally extending passage throughout most of the length of said passages, the length of the flow passages for the coating material being greater than the length of the helicoid in a direction parallel to the direction of movement of the core.

Claim 9

The extruder cross-head assembly described in claim 7 characterized by the branch passages and the portion of the longitudinally extending passage that extends in a direction counter to the direction of movement of the core being grooves in the outside surface of the helicoid, and the portion of the longitudinally extending passage that extends in the direction of the movement of the core being formed by a clearance between the helicoid and the core guide, the combined length of either of the branch passages and the longitudinally extending passage being more than twice as long as the helicoid in the direction of movement of the core.

Claim 10

The extruder cross-head assembly described in claim 1 including a cross-head having a bore opening therethrough and longitudinally thereof, a helicoid that fits within the bore and that itself has a longitudinal bore extending therethrough, the core guide having an outside sUrface that confronts the wall of the bore through the helicoid, grooves in the outside surface of the helicoid forming with other overlying surface areas of the cross-head the separate parts of the longitudinally extending passage that extend in a direction counter to the direction of movement of the core, the limit of extent of the helicoid in a direction counter to the direction of movement of the core being spaced from the cross-head and from one end of the core guide around the full circumference of the helicoid to provide an annular portion of the longitudinally extending passage, a portion of the passage that curves from a rearwardly extending direction to a forwardly extending position, the helicoid having an underside surface spaced from the core guide and providing a portion of the forwardly extending length of the longitudinally extending passage, and an extruder die confronting the other end of the core guide and having clearance from the die through which coating material is extruded over the traveling core.

Claim 11

The extruder cross-head assembly described in claim 9 characterized by a counter bore in the cross-head that holds a part of the core guide that is remote from the die end of the core guide, the counter bore having an inside diameter larger than the outside diameter of an adjacent part of the core guide, and adjusting screws at angularly spaced locations around the counter bore and threaded through the cross-head into contact with the core guide for adjusting the alignment of the core guide with respect to the helicoid to alter the clearance between the confronting faces of the helicoid and the core guide and the resulting radial depth of the longitudinally extending passage on the different sides thereof.